POS0901 INTERSTITIAL LUNG DISEASE IN MIXED CONNECTIVE TISSUE DISEASE: CLINICAL AND SEROLOGICAL ASSOCIATIONS
Authors: M. Silvério-António, J. Martinho, A. T. Melo, F. Guimarães, D. Santos Oliveira, J. M. Pestana Lopes, A. Saraiva, L. Gago, A. M. Gomes Correia, A. L. Fernandes, S. P. Dinis, R. Nicolau, S. P. Silva, C. Costa, T. Beirão, A. Furtado, P. M. Azevedo Abreu, C. Afonso, D. Peixoto, E. Dourado, N. Khmelinskii
Journal: Annals of the Rheumatic Diseases (2022)

Background Mixed connective tissue disease (MCTD) is a rare systemic rheumatic disease characterized by the expression of autoantibodies targeting the U1-ribonucleoprotein and overlapping clinical features of systemic sclerosis, systemic lupus erythematosus, and inflammatory myopathies. Interstitial lung disease (ILD) is present in 47% to 78% of patients and has been associated with higher mortality rates. Associations of ILD with Raynaud’s phenomenon, dysphagia, anti-Ro52 antibodies, and a scleroderma pattern on nailfold capillaroscopy have been reported in MCTD patients. Objectives This study aims to identify clinical and serological associations and independent predictors of ILD for patients with MCTD. Methods Multicenter retrospective study using data collected from clinical records. Adult patients who underwent lung computed tomography (CT) and met at least one of four MCTD diagnostic criteria (Sharp, Alarcón-Segovia, Kasukawa, or Kahn criteria) were included. Univariate analysis was performed using Chi-Square, Fischer’s Exact, and Mann-Whitney tests, as appropriate. Multivariate analysis was performed using binary logistic regression modelling. The linearity of the continuous variables concerning the logit of the dependent variable was assessed via the Box-Tidwell procedure. Cases with missing information and outliers were excluded from the multivariate analysis to fulfil all assumptions necessary to assure the validity of the regression. Results Fifty-seven patients, of whom 37 were Caucasian (64.9%) and 48 were females (84.2%), with a mean age of 39.4±14.0 years, were included. Twenty-seven patients had ILD (47.4%), of whom 22 had nonspecific interstitial pneumonia (81.5%), 4 had usual interstitial pneumonia (14.8%), and 1 had lymphoid interstitial pneumonia (3.7%) pattern on CT. Among patients with ILD, 13 were asymptomatic (48.1%), while 14 had respiratory symptoms (51.9%), including dyspnea (N=13, 48.1%), cough (N=7, 25.9%), and pleuritic chest pain (N=1, 3.7%). Pulmonary function tests were performed in 22 patients (81.5%), 20 of whom had a restrictive pattern (90.9%). In the univariate analysis, lymphadenopathy at disease onset (22.2% vs 3.3%, p=0.045) and esophageal involvement at any time point (40.7% vs 16.7%, p=0.043), were associated with ILD. The binary logistic regression model predicting ILD included 56 patients, and the model explained 36.5% (Nagelkerke R2) of the variance in ILD and correctly classified 75% of all cases. Older age at diagnosis (OR 1.10/year, 95%CI: 1.00-1.12, p=0.046) and lymphadenopathy at disease onset (OR 19.65, 95%CI: 1.91-201.75, p=0.012) were identified as predictors of ILD in MCTD patients, irrespective of sex and esophageal involvement. Conclusion Older age at diagnosis and lymphadenopathy at disease onset were independent predictors of ILD in MCTD. Therefore, these factors should be considered when evaluating MCTD patients, especially at the time of diagnosis. To the best of our knowledge, this is the largest study ever describing predictors of ILD for MCTD patients. References [1]Fagundes MN, Caleiro MT, Navarro-Rodriguez T, Baldi BG, Kavakama J, Salge JM, Kairalla R, Carvalho CR. Esophageal involvement and interstitial lung disease in mixed connective tissue disease. Respir Med. 2009 Jun;103(6):854-60. doi: 10.1016/j.rmed.2008.12.018. Epub 2009 Feb 6. PMID: 19201182. [2]Gunnarsson R, Aaløkken TM, Molberg Ø, Lund MB, Mynarek GK, Lexberg AS, Time K, Dhainaut AS, Bertelsen LT, Palm O, Irgens K, Becker-Merok A, Nordeide JL, Johnsen V, Pedersen S, Prøven A, Garabet LS, Gran JT. Prevalence and severity of interstitial lung disease in mixed connective tissue disease: a nationwide, cross-sectional study. Ann Rheum Dis. 2012 Dec;71(12):1966-72. doi: 10.1136/annrheumdis-2011-201253. Epub 2012 May 1. PMID: 22550317 Disclosure of Interests None declared